Re: [PATCH v2 01/13] dt-bindings: gpio: add common schema for GPIO controllers

[Laurent Pinchart]

Hi Krzysztof,

Thank you for the patch.

On Thu, Sep 17, 2020 at 06:52:49PM +0200, Krzysztof Kozlowski wrote:
> Convert parts of gpio.txt bindings into common dtschema file for GPIO
> controllers.

How about deleting the part that has been converted from gpio.txt ?

> The schema enforces proper naming of GPIO controller nodes and GPIO
> hogs.
> 
> The schema should be included by specific GPIO controllers bindings.

Instead of including it manually, could we use a conditional select: to
apply the schema automatically when a gpio-controller property is
present ?

> Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> 
> ---
> 
> Changes since v1:
> 1. Do not require compatible (some child nodes are gpio-controllers
>    without the compatible).
> ---
>  .../devicetree/bindings/gpio/gpio-common.yaml | 125 ++++++++++++++++++
>  1 file changed, 125 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/gpio-common.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/gpio-common.yaml b/Documentation/devicetree/bindings/gpio/gpio-common.yaml
> new file mode 100644
> index 000000000000..af9f6c7feeec
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/gpio-common.yaml
> @@ -0,0 +1,125 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/gpio-common.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Common GPIO controller properties
> +
> +maintainers:
> +  - Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> +  - Linus Walleij <linus.walleij@xxxxxxxxxx>
> +
> +properties:
> +  nodename:
> +    pattern: "^(gpio-controller|gpio)(@[0-9a-f]+|-[0-9a-f]+)?$"
> +
> +  '#gpio-cells': true
> +  gpio-controller: true
> +  gpio-ranges: true
> +
> +  gpio-line-names:
> +    description: |
> +      Optionally, a GPIO controller may have a "gpio-line-names" property. This
> +      is an array of strings defining the names of the GPIO lines going out of
> +      the GPIO controller. This name should be the most meaningful producer
> +      name for the system, such as a rail name indicating the usage. Package
> +      names such as pin name are discouraged: such lines have opaque names
> +      (since they are by definition generic purpose) and such names are usually
> +      not very helpful.
> +
> +      For example "MMC-CD", "Red LED Vdd" and "ethernet reset" are reasonable
> +      line names as they describe what the line is used for. "GPIO0" is not a
> +      good name to give to a GPIO line.
> +
> +      Placeholders are discouraged: rather use the "" (blank string) if the use
> +      of the GPIO line is undefined in your design. The names are assigned
> +      starting from line offset 0 from left to right from the passed array. An
> +      incomplete array (where the number of passed named are less than ngpios)
> +      will still be used up until the last provided valid line index.
> +
> +  gpio-reserved-ranges:
> +    description:
> +      Indicates the start and size of the GPIOs that can't be used.
> +
> +  ngpios:
> +    description: |
> +      Optionally, a GPIO controller may have a "ngpios" property. This property
> +      indicates the number of in-use slots of available slots for GPIOs. The
> +      typical example is something like this: the hardware register is 32 bits
> +      wide, but only 18 of the bits have a physical counterpart. The driver is
> +      generally written so that all 32 bits can be used, but the IP block is
> +      reused in a lot of designs, some using all 32 bits, some using 18 and
> +      some using 12. In this case, setting "ngpios = <18>;" informs the driver
> +      that only the first 18 GPIOs, at local offset 0 .. 17, are in use.
> +
> +      If these GPIOs do not happen to be the first N GPIOs at offset 0...N-1,
> +      an additional set of tuples is needed to specify which GPIOs are
> +      unusable, with the gpio-reserved-ranges binding.
> +
> +patternProperties:
> +  "^(hog-[0-9]+|.+-hog(-[0-9]+)?)$":
> +    type: object
> +    description:
> +      The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
> +      providing automatic GPIO request and configuration as part of the
> +      gpio-controller's driver probe function.
> +      Each GPIO hog definition is represented as a child node of the GPIO controller.
> +
> +    properties:
> +      gpio-hog: true
> +      gpios: true
> +      input: true
> +      output-high: true
> +      output-low: true
> +      line-name:
> +        description:
> +          The GPIO label name. If not present the node name is used.
> +
> +    required:
> +      - gpio-hog
> +      - gpios
> +
> +    oneOf:
> +      - required:
> +          - input
> +      - required:
> +          - output-high
> +      - required:
> +          - output-low
> +
> +    additionalProperties: false
> +
> +required:
> +  - "#gpio-cells"
> +  - gpio-controller
> +
> +examples:
> +  - |
> +    gpio-controller@15000000 {
> +        compatible = "foo";
> +        reg = <0x15000000 0x1000>;
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +        ngpios = <18>;
> +        gpio-reserved-ranges = <0 4>, <12 2>;
> +        gpio-line-names = "MMC-CD", "MMC-WP", "VDD eth", "RST eth", "LED R",
> +                          "LED G", "LED B", "Col A", "Col B", "Col C", "Col D",
> +                          "Row A", "Row B", "Row C", "Row D", "NMI button",
> +                          "poweroff", "reset";
> +    };
> +
> +  - |
> +    gpio-controller@1400 {
> +        compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
> +        reg = <0x1400 0x18>;
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +
> +        line-b-hog {
> +            gpio-hog;
> +            gpios = <6 0>;
> +            input;
> +            line-name = "foo-bar-gpio";
> +        };
> +    };

-- 
Regards,

Laurent Pinchart